There are many occasions when you want to save data in form of objects. An object is a memory stream, which is hard to write using the normal methods. In this article, I show how you can save objects in a database and read back from the database.

Note: Please Execute tst.sql in MS-SQL.

This code shows how to save objects in a database. An object can be easily by using Serializing and ADO.NET. The Serialize method of BinaryFormatter class serializes an object, or graph of connected objects, to the given stream. The Deserialize method of BinaryFormatter deserializes the stream into an object graph.

The MemoryStream class of the .NET framework library uses memory as a data storage. MemoryStream encapsulates data stored as an unsigned byte array that is initialized upon creation of a MemoryStream object, or the array can be created as empty. The encapsulated data is directly accessible in memory. Memory streams can reduce the need for temporary buffers and files in an application.

An stream is an array of bytes and data storage. In this program, I create an object of class Car and read data in a BinaryFormatter object. After that I create a DataSet object and use BinaryFomatter class object and set DataTable's field value to the object.

Imports System
Imports System.IO
Imports System.Data
Imports System.Data.SqlClient
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters.Binary
<Serializable()> _
Public Class Car
Public name As String
Public age As Integer
Public Sub New(ByVal name As String, ByVal age As Integer)
Me.name = name
Me.age = age
End Sub 'New
Public Sub Up()
age += 1
End Sub 'Up
End Class 'Car_
Public Class Test
Public Shared Sub Main()
Console.Write("name:")
Dim sname As String = Console.ReadLine()
Console.Write("age:")
Dim sage As String = Console.ReadLine()
Dim car As New Car(sname, Int32.Parse(sage))
Dim ms As New MemoryStream
Dim b As New BinaryFormatter
b.Serialize(ms, car)
Dim con As New SqlConnection("server=localhost;uid=sa;pwd=;database=test")
con.Open()
Dim ad As New SqlDataAdapter("select * from tst", con)
Dim ds As New DataSet
ad.Fill(ds, "tblFile")
Dim dbTable As DataTable = ds.Tables("tblFile")
Dim dbRow As DataRow = dbTable.NewRow()
' Store data in the row
dbRow("id") = "kimlee"
dbRow("obj") = ms.GetBuffer()
dbRow("len") = ms.Length
dbTable.Rows.Add(dbRow)
' Update data source
Dim cb As New SqlCommandBuilder(ad)
ad.Update(ds, "tblFile")
Dim comd As New SqlCommand("select * from tst", con)
Dim sr As SqlDataReader = comd.ExecuteReader()
While sr.Read()
Dim cc(CInt(sr("len"))) As Byte
sr.GetBytes(1, 0, cc, 0, CInt(sr("len")))
Dim mss As New MemoryStream(cc)
Dim dcar As Car = CType(b.Deserialize(mss), Car)
dcar.Up()
Console.Write("name:")
Console.WriteLine(dcar.name)
Console.Write("age:")
Console.WriteLine(dcar.age)
End While
con.Close()
End Sub 'Main
End Class 'Test